ui_testing_blob.kt

    @Test
    fun mainActivityTest() {
        val bottomNavigationItemView = onView(
            allOf(
                withId(R.id.navigation_dashboard), withContentDescription("Dashboard"),
                childAtPosition(
                    childAtPosition(
                        withId(R.id.navigation),
                        0
                    ),
                    1
                ),
                isDisplayed()
            )
        )
        bottomNavigationItemView.perform(click())

        val bottomNavigationItemView2 = onView(
            allOf(
                withId(R.id.navigation_notifications), withContentDescription("Notifications"),
                childAtPosition(
                    childAtPosition(
                        withId(R.id.navigation),
                        0
                    ),
                    2
                ),
                isDisplayed()
            )
        )
        bottomNavigationItemView2.perform(click())

        val textView = onView(
            allOf(
                withId(R.id.message), withText("Notifications"),
                childAtPosition(
                    allOf(
                        withId(R.id.container),
                        childAtPosition(
                            withId(android.R.id.content),
                            0
                        )
                    ),
                    0
                ),
                isDisplayed()
            )
        )
        textView.check(matches(withText("Notifications")))

        val bottomNavigationItemView3 = onView(
            allOf(
                withId(R.id.navigation_home), withContentDescription("Home"),
                childAtPosition(
                    childAtPosition(
                        withId(R.id.navigation),
                        0
                    ),
                    0
                ),
                isDisplayed()
            )
        )
        bottomNavigationItemView3.perform(click())

        val textView2 = onView(
            allOf(
                withId(R.id.message), withText("Home"),
                childAtPosition(
                    allOf(
                        withId(R.id.container),
                        childAtPosition(
                            withId(android.R.id.content),
                            0
                        )
                    ),
                    0
                ),
                isDisplayed()
            )
        )
        textView2.check(matches(withText("Home")))
    }

    private fun childAtPosition(
        parentMatcher: Matcher<View>, position: Int
    ): Matcher<View> {

        return object : TypeSafeMatcher<View>() {
            override fun describeTo(description: Description) {
                description.appendText("Child at position $position in parent ")
                parentMatcher.describeTo(description)
            }

            public override fun matchesSafely(view: View): Boolean {
                val parent = view.parent
                return parent is ViewGroup && parentMatcher.matches(parent)
                        && view == parent.getChildAt(position)
            }
        }
    }